Method for preparing tubular graphene composite membrane

ABSTRACT

A method for preparing a graphene composite membrane on the surface of a tubular support. In the method, a tubular ceramic membrane is used as the support, a layer of graphene material is uniformly prepared on the surface of the support by vacuum suction, and the defect-free tubular graphene composite membrane is obtained by the drying process.

TECHNICAL FIELD

The Invention belongs to the field of new material technology, relatingto a method for preparing tubular graphene composite membrane, andparticularly to a method for preparing a continuous defect-free graphenecomposite membrane on the surface of a tubular support.

BACKGROUND ART

With high yield of separation, low energy consumption and thecharacteristic of easy integration with catalytic reaction and otherprocess combinations, membrane separation as a new and efficientseparation technology recently has become an important means to solvethe key problems concerning energies, resources and environment faced bymodern human and an important part of development strategy to realizethe economic sustainability. As the membrane separation is of aseparation process based on materials, membrane material is a keyelement of the membrane separation technology.

Graphene is a two dimensional nano material, consisting of a graphitemonolayer with the thickness of atomic layer. This kind of material hastremendous potential with various excellent properties. With strongelectrical and thermal conductivities and mechanical strength, highcarrier mobility and transmittance and huge specific area, the materialshows a great application prospect in multiple fields such astransparent conducting thin film, electron device, energy storage,catalysis, biomedicine and separation, etc. In addition, as thederivatives of graphene material, sulfhydrylated graphene, oxidizedgraphene, hydroxylated graphene, aminated graphene and carboxylatedgraphene also show their attractive prospect in different fields fortheir different special functional groups.

Graphene and its derivatives have shown good prospects in recent yearsas the researches on the materials for preparing membrane have gainedmuch attention (Science 335, 442 (2012), Science 342, 95 (2013), Science342, 91 (2013)). However, the current graphene (and its derivative)membrane is mainly flat membrane prepared with the methods asfiltration, spin-coating and dip-coating. There is no special method forpreparing a tubular graphene (and its derivative) membrane yet. Tubularmembrane has the characteristics as large loading density and simpleoperation. However, for the large surface curvature and long and thinshape of the tubular support, the tubular graphene composite membrane isdifficult to be prepared with the methods as filtration, spin-coatingand dip-coating. Therefore, it has a significant application prospect todevelop a simple and easy method for preparing tubular graphenecomposite membrane, which is beneficial to the industrializedapplication of graphene materials.

SUMMARY OF THE INVENTION

The Invention provides a method for preparing tubular graphene compositemembrane. In the method, a porous tubular ceramic membrane is used as asupport and a layer of graphene material is uniformly prepared on thesurface of the support through vacuum suction.

The technical scheme of the Invention is a method for preparing tubulargraphene composite membrane; the specific steps are as follows:

(1) Preprocessing of a support: selecting a tubular ceramic membrane asa support; drying it after flushing with water; sealing one end of thesupport with a sealant and connecting the other end to a vacuum pumpthrough a pipeline;

(2) Preparation of a membrane preparing solution: dissolving a graphenematerial into a solvent; obtaining a uniformly dispersed membranepreparing solution through ultrasonic processing;

(3) Preparation of membrane: immersing the tubular support processed inStep (1) in the membrane preparing solution; starting the vacuum pumpand holding for 1-12 hours after the pressure is stabilized;

(4) Placing the prepared membrane in a vacuum drying oven and dry themembrane under 25° C.-50° C.

In Step (1), the tubular ceramic membrane is preferably a single tubularsupport, a multi-channel tubular support, a single tubular hollow fibersupport, a multi-channel hollow fiber or a honeycomb ceramic support;the material of the ceramic support is preferably one or two of ZnO₂,Al₂O₃, TiO₂ or ZrO₂.

In Step (1), the sealant is preferably one of polyurethane sealant,phenolic resin sealant, silicone sealant, vulcanized silicone sealant,epoxy resin sealant or polyacrylic resin sealant.

In Step (2), the solvent is preferably one of water, ethyl alcohol, DMF,methyl alcohol or DMSO.

In Step (2), the solvent is preferably one of graphene, sulfhydrylatedgraphene, oxidized graphene, hydroxylated graphene, aminated graphene,or carboxylated graphene.

In Step (2), the concentration of the membrane preparing solution ispreferably 0.001-1 mg/mL.

In Step (3), the stabilized pressure of the vacuum pump is preferably100-2000 Pa.

Beneficial Effects

The method provides a simple and easy way for preparing a continuousdetect-free graphene composite membrane on the surface of a tubularsupport. The method has a universality for preparing all kinds ofgraphene derivative membranes. It makes full use of the performanceadvantages of the graphene material in membrane separation and has asignificant meaning for large-scale graphene material application thefield of membrane.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the membrane preparing device;

FIG. 2 is a picture of the real single tubular support in Embodiment 1;

FIG. 3 is a picture of the real 19-channel tubular support in Embodiment2;

FIG. 4 is a picture of the real single tubular hollow fiber inEmbodiment 3;

FIG. 5 is an electronic microscope photograph of the surface of theoxidized graphene membrane prepared in Embodiment 3;

FIG. 6 is an electronic microscope photograph of the cross section ofthe oxidized graphene membrane prepared in Embodiment 3;

FIG. 7 is a result figure of methanol/water separation of the oxidizedgraphene membrane prepared in Embodiment 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments in combination with the technical scheme are as follows:

Embodiment 1 Preparing a Graphene Membrane on the Surface of the SingleTubular Support With the Method Therein

(1) Preprocessing of a support : selecting a single tubular ceramicmembrane (ZrO₂/Al₂O₃) as a support (as shown in FIG. 2); drying it afterflushing with water; sealing one end of the support with phenolic resinsealant and connecting the other end to a vacuum pump with a pipelinethrough a surge flask and a pressure regulating valve, as shown in FIG.1.

(2) Preparation of a membrane preparing solution: dissolving thegraphene into DMF with a concentration of 0.001 mg/mL; obtaining auniformly dispersed membrane preparing solution through ultrasonicprocessing.

(3) Preparation of membrane: immersing the tubular support processed inStep 1 in the membrane preparing solution; starting the vacuum pump andholding for 12 hours after the pressure is stabilized at 1000 Pa.

(4) Placing the prepared membrane in a vacuum drying oven and drying themembrane under 40° C.

Through single component characterization for H₂, N₂, CO₂ and CH₄ of thegraphene membrane, the result shows that the membrane has favorablehydrogen selectivity and the ideal selectivity of H₂/N₂, H₂/CO₂ andH₂/CH₄ reaches 67, 85 and 139 respectively.

Embodiment 2 Preparing a Animated Graphene Membrane on the Surface ofthe 19-Channel Tubular Support With the Method Therein

(1) Preprocessing of a support: selecting a 19-channel tubular ceramicmembrane (TiO₂/Al₂O₃) as a support (as shown in FIG. 3); drying it afterflushing with water; sealing one end of the support with polyurethanesealant and connecting the other end to a vacuum pump through apipeline, as shown in FIG. 1.

(2) Preparation of a membrane preparing solution: dissolving theaminated graphene into ethyl alcohol with a concentration of 0.03 mg/mL;obtaining a uniformly dispersed membrane preparing solution throughultrasonic processing.

(3) Preparation of membrane: immersing the tubular support processed inStep 1 in the membrane preparing solution; starting the vacuum pump andholding for 5 hours after the pressure is stabilized at 2000 Pa.

(4) Placing the prepared membrane in a vacuum drying oven and drying themembrane under 25° C.

Through single component characterization for H₂, N₂, CO₂ and CH₄ of theaminated graphene membrane, the result shows that the membrane hasfavorable CO₂ selectivity and the ideal selectivity of CO₂/N₂ andCO₂/CH₄ reaches 35 and 72 respectively.

Embodiment 3 Preparing an Oxidized Graphene Membrane on the Surface ofthe Single Tubular Hollow Fiber (Al₂O₃) With the Method Therein

(1) Preprocessing of a support : selecting a single tubular hollow fiberas a support (as shown in FIG. 4); drying it after flushing with water;sealing one end of the support with polyacrylic resin sealant andconnecting the other end to a vacuum pump through a pipeline, as shownin FIG. 1.

(2) Preparation of a membrane preparing solution: dissolving theoxidized graphene into water with a concentration of 0.1 mg/mL;obtaining a uniformly dispersed membrane preparing solution throughultrasonic processing.

(3) Preparation of membrane: immersing the tubular support processed inStep 1 in the membrane preparing solution; starting the vacuum pump andholding for 3 hours after the pressure is stabilized at 100 Pa.

(4) Placing the prepared membrane in a vacuum drying oven and drying themembrane under 50° C. The electronic microscope photographs of thesurface and cross section of the prepared oxidized graphene membrane areas shown in FIGS. 5 and 6. From the figures, it can be seen that theprepared graphene is of layer structure with a smooth and completesurface.

Through methanol/water pervaporation characterization for oxidizedgraphene membrane, the result (in FIG. 7) shows that the membrane hasfavorable water permeability with a max. separation factor of 42.

Embodiment 4 Preparing a Carboxylated Graphene Membrane on the Surfaceof the Honeycomb Ceramic Support With the Method Therein

(1) Preprocessing of a support: selecting a honeycomb ceramic (ZnO₂) asa support; drying it after flushing with water; sealing one end of thesupport with silicone sealant and connecting the other end to a vacuumpump through a pipeline, as shown in FIG. 1.

(2) Preparation of a membrane preparing solution: dissolving thehydroxylated graphene into DMSO with a concentration of 1 mg/mL;obtaining a uniformly dispersed membrane preparing solution throughultrasonic processing;

(3) Preparation of membrane: immersing the tubular support processed inStep 1 in the membrane preparing solution; starting the vacuum pump andholding for 1 hour after the pressure is stabilized at 500 Pa.

(4) Placing the prepared membrane in a vacuum drying oven and drying themembrane under 30° C.

Through ethyl alcohol/water pervaporation characterization forcarboxylated graphene membrane, the result shows that the membrane hasfavorable water permeability with a max. separation factor of 63.

What is claimed is:
 1. A method for preparing tubular graphene compositemembrane; the specific steps are as follows: (1) Preprocessing of asupport: selecting a tubular ceramic membrane as a support; drying itafter flushing with water; sealing one end of the support with a sealantand connecting the other end to a vacuum pump with a pipeline; (2)Preparation of a membrane preparing solution: dissolving a graphenematerial into a solvent; obtaining a uniformly dispersed membranepreparing solution through ultrasonic processing; (3) Preparation ofmembrane: immersing the tubular support processed in Step (1) in themembrane preparing solution; starting the vacuum pump and holding for1-12 hours after the pressure is stabilized; (4) Placing the preparedmembrane in a vacuum drying oven and dry the membrane under 25° C.-50°C.
 2. The method according to claim 1, wherein, the support of thetubular ceramic membrane can be a single tubular support, amulti-channel tubular support, a single tubular hollow fiber support, amulti-channel hollow fiber or a honeycomb ceramic support.
 3. The methodaccording to claim 1, wherein, the material of the tubular ceramicmembrane support can be one or two of ZnO₂, Al₂O₃, TiO₂ or ZrO₂.
 4. Themethod according to claim 1, wherein, the sealant can be one ofpolyurethane sealant, phenolic resin sealant, silicone sealant,vulcanized silicone sealant, epoxy resin sealant or polyacrylic resinsealant.
 5. The method according to claim 1, wherein, the solvent can beone of water, ethyl alcohol, DMF, methyl alcohol or DMSO.
 6. The methodaccording to claim 1, wherein, the graphene material can be one ofgraphene, sulfhydrylated graphene, oxidized graphene, hydroxylatedgraphene, aminated graphene, or carboxylated graphene.
 7. The methodaccording to claim 1, wherein, the concentration of the membranepreparing solution is 0.001-1 mg/mL.
 8. The method according to claim 1,wherein, the pressure of the vacuum pump is 100-2000 Pa.